You here a sound. It was faint at first, just at the edge of one's hearing, but as the wind kicked up, the sound came in clearer, louder. A screeching, grinding wail, rhythmically pulsing like the beat of a human heart. A light appeared, shimmering in time, and with every pulse grew brighter. Then, with a clunk and a whir, a large blur police box solidified, the wail petering off into a gentle sub-sonic hum. The Door on the side of the police box opens and a tall thin man pops out.
"Hello, I'm the Doctor." To the uneducated observer, this tall thin man looked like some kind of crazed old-fashioned professor, with his tweed jacket and suspenders and bow-tie, but he was too young to be a professor, his hair hair coiffed in some kind of ridiculous pompadour. But his eyes, his eyes gave away what he really was. They were eyes that had seen empires rise, galaxies come into being, stars being born, and all of them return to dust. Eyes that had seen everything. Eyes that right now were looking rather confused.
"Oh, I am terribly sorry madam," He said after looking around. "I seem to have wandered into here by mistake. I'll be going now." And with those words the man popped back into his box and, in a inverted but similar method to its arrival, the police box vanishes. As the last waves of sound fade an average sized, average blond man in a black duster comes charging around a corner with a black backpack in hand.
"Think fast." He says, tossing you the bag as he runs by. "It's a bag of holding. Have fun and try not to maim anyone." Just as he finishes he goes around another corner.